1. Field of the Invention
The present invention relates to optical switches, and particularly to a scalable matrix optical switch arrangement.
2. Discussion of the Known Art
U.S. Pat. No. 5,206,497 (Apr. 27, 1993) discloses free-space optical switching apparatus. A light beam-carrying optical fiber is coupled to a collimated beam launcher, and the trajectory of the beam in space is adjusted by a servo-controlled motor driven positioning mechanism. The beam is steered by the adjusting mechanism toward a selected one of a number of photo receptors each of which has a corresponding optical fiber leading from the receptor. A component of the free-space beam is split by a mirror and reflected toward an area sensor. An output of the sensor is applied to a processor/controller which, in turn, controls the trajectory adjusting mechanism to insure that the beam remains incident on a selected photoreceptor.
Applications exist wherein numerous light-modulated signals carried by respective optical fibers must be switched for routing among a corresponding number of output fibers, within relatively short switching times and without significant cross-talk among the fibers. Known guided wave matrix switch arrangements operate by directing light beams inside crystalline blocks. These arrangements are not entirely satisfactory in that they are sensitive to the state of polarization (SOP) of the light beams. Each element of the switch exhibits an insertion loss of around 11/2 dB, and they produce 20 dB cross-talk at best. Also, the number of optical elements needed to realize an N-input by N-output optical guided wave switch, is on the order of 2N*log.sub.2 N to N.sup.2 elements depending on the switch architecture. For a large scale, e.g., 4096.times.4096 matrix switch, a crystalline guided wave optical switch arrangement does not provide a practical solution.